Construction for glass melting tanks



NOV. 28, 1944. w E U E 2,363,954

CONSTRUCTION FOR GLASS MEL'IING TANKS Filed June 5, 1942 2 Sheets-Sheet1 gwue/wkvrl a /14. sue F Gnu/V0 Nov. 28, 1944. w. F. GAUNDER 2,363,954

CONSTRUCTION FOR GLASS MELTING TANKS Filed June 5, 1942 2 Sheets-Sheet 2MIL e we F. 6n UNDER Patented Nov. 28

Wilbur F. Gaunder, Mount Vernon,' 0hio, as-

slgnor to Pittsburgh Plate Glass Company.-

Allegheny County, 1a., a corporation sylvania of Penn-v Application June5, 1942, Serial No. 445,908

Thisinvention relates to the control of molten glass baths and it hasparticular relation to aplarly downward along the side walls as thecooler glass sinks and the warmer upper glass moves paratus designed toaid in refining molten glass preparatory to withdrawing ,it from thebath.

One object of the invention is to provide an improved arrangement ofstructure in a tank for diverting impurities in a bath of molten glassbefore they reach glass drawing chambers and returning such impuritiesfor further refinement in the body of the bath.

Another object of the invention is to provide an improved tank formolten glass wherein the portions thereof can be controlled as todirection of movement.

Another object of the invention is to provide in to take its place. Thisglasscontaminated with impurities, including refractory, solution, willbecome involved in eddy currents and will mix with the better quality ofglass somewhat animproved skim kiln or compartment in connection with atank for molten glass to divert impurities or unrefined glassingredients from the location of withdrawal of the glass from the In theoperation 0! ,a glass melting tank or furnace, particularly the typeemployed-in connectionwith the drawing of window glass, it'has beenrecognized that the better quality of glass passes down the centralportion of the tank to molten glass bath is composed of.refractoryblocks and as the body of the bath moves forward toward the drawingendof the tank, the side walls thereof are at least slightly cooler thanthe inner portion of the bath. Impurities,

such as incompletely reacted glass batch, products of erosion along therefractory walls, foam, etc., tend to collect and move toward and alongthe side walls of the tank. Since the tank walls are somewhat coolerthan the body of the tank,

f there is retardation of reaction of the glass ingradients along thisarea.

Solution from the tank basin walls may form in effectga protective'shelf for the partially refined glass as it proceeds along the wallswhere it is shielded from full effect of the heat. Convection currentsmove from the center of the bath towards the walls, particularly in theupper strata of the. bath where poorer quality is more pronounced.Convection currents also move vertically and anguthe so-oalled centraldrawing chambers at the alternate arrangements of elements associatedclose to the walls. It is recognized that the lower portion of themolten glass bathbelow its surface moves in a reverse direction; thatis, back toward the hotter body portion nearer the charging or rear endof the tank.

According to this invention, the characteris tics-discussed above 'ofthe molten glass bath in the tank are taken advantage of in designingtank walls and in adding elementsin such man'- ner as to improve thegeneral quality of the glass in the side drawing chambersjas well as inthe end drawing chambers, and more completely to control, the action ofthe bath in its tendencies toward movement.

In the drawings:

Fig. 1 is a fragmentary horizontal section showing diagrammatically aglass melting tank or furnace: Fig. 2 is a fragmentary plan,-on a largerscale, of a skim kiln or'compar'tment; Fig. 3 is a fragmentary verticalsection taken substantially along the line III-III of Fig. 2; Fig. 4 isa fragmentary vertical section taken [substantially along the line IVIVofFig. 2 and illustrating added adjusting mechanism; and Fig. 5 is afragmentary plan of a skim kiln and therewith.

In one form of the invention there is provided a glass melting, tank Illadapted to contain a molten glass bath which moves generally from a rearbatch-charging end 2i toward a drawing end of the tank where frontdrawing chamhere 2i and side drawing chambers 25 are formed. During thetank operation, the glass ingredients are melted and maintained inmoltenstate by means of flames from suitable fuel fed through side ports21 along the sides of-the tank. In

this type of apparatus, known as a regenerative tank, the flames areplayed over the surface or the bath alternately at proper intervals fromopposite sides of the tank: Ordinarily tanks of this type are operatedcontinuously over con- ,siderable periods of time."

Beforeentering the forward portion of the sides surface impurities thatmay collect or form upon the bath. Skim kilns or compartments 30 onopposite sides of the tank are formed either forward or rearward of thelocation of the floater. A refractory floater 35 disposed across eachkiln 30 at its mouth is positioned in guides 36 formed in the oppositewalls of the kiln. The floater can be made to ride at the desired depthupon the molten bath by hollowing out to proper depth upper portionsthereof, as indicated at 31.

A bridge 40 of refractory in slab form traverses the skim kiln 30 insubstantially horizontal direction and its opposite ends are slidablymounted in guides 4| formed vertically in the opposite inner .is spacedfrom the bottom of the tank.

It is to be understood that the bath inside the kiln is maintained atsomewhat lower temperature than the body of the glass bath and thatthehotter molten glass drifts toward the cooler mass in the kiln.Therefore, along the sides of the tank, the hotter glass which moves thefloater can serve asa trap to catch and direct impurities into the kilnwithout the need of having allof them pass undeneath such floater inentering the kiln.

Although several arrangements of structure have been shown and describedin detail, itwill be apparent to those skilled in the art that theinvention is not so limited; but that various changes can be madetherein without departing from the spirit of the invention or from thescope, of the appended claims.

I claim:

1. In a glass melting tank for containing a molten glass bath atpredetermined level and including side walls running longitudinallyforwardly and rearwardly of the tank, compartments on opposite sides ofthe tank having forward and rearward walls defining mouths openinglaterally at said side walls into the body of the tank, oblongrefractory bars disposed substantially longitudinally with respect tosaid side walls and extending between forward and reartoward theentrance of the kiln is drawn into the latter beneath the floater andover the top of the bridge 40. As it becomes cooler, the surface glassin the kiln sinks to such depth as to be able to pass beneath the bridgeback to the body of the bath. Since there is movement in the tank basinof the lower body of the bath back toward the charging end, theimpurities along the marginal portions of the bath are thus returned tothe hotter portions of the tank for further refinement.

In order to maintain the bridge 40 in proper position in the guides 4 Ior to adjust its position therein, an arm 43 having a downwardlyprojecting finger 45 at one end thereof, rests upon a piece ofrefractory 46 that is disposed upon each end portion of the bridge. Eacharm has an intermediate pivot connection 411 securing it to a support48, and the arm end opposite the finger. 46 is provided with a bolt 49screw-threaded therein and adapted to contact the upper surface of thesupport. Since the bridge tends to float in the molten bath surface andto cause the bolt 49 to be pressed downwardly on the support, the arm 43can be adjusted to hold the bridge at the desired depth below thesurface ofv the bath.

In thearrangement shown in Fig. 5, a bridge 40 and its mountings in thewalls of the kiln 30 are the same as those described with reference toFig. 2. However, another form of floater 50 is shown, which is disposedacross the mouth of the kiln; that is; it floats upon the body of thebath along the inside line of the tank wall. This floater is hollowedout, as indicated at 5|, and the end 53 thereof that faces rearwardly isinclined or beveled to define an acute angle with the adjacent tankwall, the apex of the angle broken lines of Fig. 5. As shown in thisfigure,

Ward compartment walls on opposite sides of the tank to control flow ofmolten glass into and out of said compartment, and means for holding therefractory bars at predetermined locations with respect to the forwardand rearward walls of the compartments.

2. In a glass melting tank for containing a molten glass bath atpredetermined level and having longitudinal side walls extending from acharging end to a withdrawing end of the tank, a compartment on one sideof the tank having a mouth opening through one side wall into the tankproper, guides in opposite walls of the compartment and being aligned ina direction longitudinally of the tank, and a floater extendingsubstantially longitudinally of the tank between the opposite walls ofsaid compartment and fitting at its opposite extremities in-said guides.

3. In a glass melting tank for containing a molten glass bath atpredetermined level and hav ing side walls, a compartment at one side ofthe tank having a mouth opening through one side wall into the body ofthe tank, and a floater traversing the mouth of the compartment, saidfloater having an inclined end surface for collecting impurities anddirecting them toward the compartment.

4. In a glass melting tank for containing a molten glass bath atpredetermined level and having longitudinal side walls, a compartmentdefined by the wall at one side of the tank and having a mouth openinglaterally into the body of the tank, a floater of refractory materialtraversing the mouth of the compartment and resting upon the surface ofthe bath to control impurities from upper marginal portions of said bathinto the compartment, and a bridge traversing an intermediate portion ofthe compartment between the bottom thereof and the level of the bath toassist in circulating the portion of the bath in the compartment backinto the lower body of said bath.

5. In a glass melting tank for containing a molten glass bath atpredetermined level and having longitudinal side walls, a compartmentdefined by the wall at one side of the tank and having a mouth openinginto the tank, a floater of refractory materialtraversing the mouth ofthe compartment and resting upon the surface of the bath, anadjustingdevice connected to the floater for moving one end thereof farther outinto the molten bath at least partially to open the mouth means forsupporting said adjusting device. 6. In a glass melting tank forcontaining a molten glass bath at predeterminedlevei and havinglongitudinal side walls, a compartment defined by the wall at one sideof the tank and having a mouth opening into the body of the tank, guidesin opposite walls of the compart; ment and extending from the tops ofsaid walls ,the bridge in the compartment, and means tor verticallyadjusting the first named means.

, 7 2,308,954 of the compartment along the bath surface, and

7. In a glass melting tank tor containing a molten glass bath atpredetermined level and having side walls, said side walls includingout-' wardly oifset compartments having mouths opening laterally intothe body of the tank for comm'unication of the molten bath to and fromsaid compartments, .a refractory slab traversing the area leading to theinterior of each compartment and disposed on the surface of the moltenglass bath, and means associated with the side walls and refractoryslabs for maintaining the latter in their traversing position on theglass bath.

WILBUR F. GAUNDER.

